On 11.5.2013 18:40, Viktor Dukhovni wrote:
On Sat, May 11, 2013 at 04:20:51PM +0200, Patrik Rak wrote:
The use case which I am interested in is basically some service sending registration confirmation messages to its users, where some users decide to fill in bogus addresses which result in temporary errors until the message expires and bounces. Such messages tend to stock pile in the deferred queue and can quite dominate the active queue and adversely affect the deliveries to proper recipients. Especially when these bogus recipients are not deferred immediately, but only after considerably long timeout.
...
One would need to size the active queue limits for some multiple of the expected 5-days of bad addresses so that such mail rarely fills the active queue. Since Postfix 1.0 was released in 2001, the price of RAM has fallen considerably. It is now quite cost-effective to build servers with 1-4 GB of RAM or more. So an MTA with this problem should have a large active queue size to avoid running out of queue slots.
BTW, perhaps I wasn't quite clear above when I said those messages dominate the queue. I meant it like their amount in the active queue is significant and prevailing, but not that they are really filling the active queue entirely. Rather than addressing the full-active-queue bottleneck (which you have most likely responded to), I was addressing the all-delivery-agents-busy bottleneck. Especially in more limited environments where increasing the delivery agent limit tenfold or more is not a viable option.
Patrik
